Evolution of planktonic foraminifera and thermocline in the southern South China Sea since 12 Ma (ODP-184, site 1143)

摘要

Down-core variation in planktonic foraminifera (PF) at Site 1143 (ODP 184) has dis- closed the evolution of upper water-column structure over the last 12 Ma in the southern South China Sea. In the early Late Miocene (-10.6-7.8 Ma), there existed a lower percentage of total Deep-dwelling species, reflecting a water thermocline deeper than that in the Middle Miocene, Which resulted from the closure of Indonesian seaway and relevant intensification of the equatorial Warm current. After the increase in deep-dwelling PF and the rising of thermocline during the late Late Miocene (7.6-6.4 Ma), the total deep-dwelling species decreased gradually from late Late Miocene (6.4 Ma) to the Pliocene, implying the deepening of water thermocline.